In broadband wireless access (BWA) networks, base stations may communicate with one or more subscriber stations by transmitting a downlink subframe which includes a preamble followed by a number of bursts. Each burst may be directed to a particular subscriber station and may be transmitted over one or several subchannels. However, channel bandwidth of some conventional BWA networks may not be used efficiently because the channel characteristics between each subscriber station and the base station may be different and may vary over time and/or frequency.
Thus, there are general needs for BWA networks and methods that make more efficient use of channel bandwidth for improved throughput.